The goal of our research is to design a computer architecture for AND-OR-parallel execution of logic programs based on the Horn clause subset of the predicate logic. We start from abstract level and move step by step towards concrete implementation details. The major contributions made in this thesis are: 1. OR-forest-a new method for describing the execution of logic programs. 2. PSOF-a process model based on parallel search of OR-forest. 3. PIM-PSOF-an abstract parallel inference machine based on PSOF model. 4. SES-PIM-a simulation and experiment system for parallel inference machine.